Reforming process and catalyst



P 3, 1953 F. G. CIAPETTA 2,651,593

REFORMING PROCESS AND CATALYST Filed March 17, 1951 3 2 a a a 5 2 a i 1X s E E 8 3 E E it 2 Q} g b poqgayyqunasag-lmagp .zaqulnN 92122200ATTEST INVENTOR.

FRANK G. CMPETTA BY W 5 Patented Sept. 8, 1953 Frank G. Cia'p'etta,

Llanerch, Pa., assignor to The Atlantic :R'efining Company,Philadelphia, Pa., a corporation of Pennsylvania Application March 17,1951, SerialNo. 216,193

(01. m an 6 Claims. .1 V I a This invention relates generally to aprocess for improving low octane hydrocarbon fractions to the nre uc ainc se in ,Qe an va of such fractions. More specifically, this inventionis concerned with a'process involying the use of a specialcatalyst underffiformingp pnditions whereby low anti-knock hydrocarbon fractions canbe eff ciently converted to a product possessing a higher anti-knockvalue.

It is well known that an increase in the antiknock properties ofhydrocarbons may be accomplished bycatalytic' reforming under specificoperating conditions. These processes generally involve the 'steps ofpassing a hydrocarbon fraction with or withdut added hydrogen over areforming catalyst. Although may theories have been advanced as to' theexact nature of the reactions which occur during reforming, it isgenerally believed that reforming involves a number ofsimultaneously-occurring reactions, such as isomerization,dehydrogenation, selective cracking, and aromatization. In recent years,a mult d o a ts hav been P p ed r t reforming of low anti-knockgasolines. These catalysts include a majority of the elements of theperiodic table in various combinations. While a number of thesecatalysts have been found to be effective, at least to some extent, inreforming hydrocarbon fractions, only a few of these catalytic agentsare of sufficient imporfiance o r c e en i e' t on fo comm rc operationsince even when an eiiectivecatalyst is found, its use will not becommercially adopted unless it displays in addition to a highyieldoctane relationship, the highly desirable andnecessary qualitiessuch as a long life, immunity to poisoning, and ease of regeneration.The mere fact that such a large number of reforming catalysts havebeensuggested the prior art is an indication of the dijfficulty involvedfinding a proper combination of chemical compounds which will have thesedesired properties.

It is an object of the present invention to provide a reforming catalystwhich produces high yield-octane relationships, has a long life, isifnmune to poisoning, and is easily regenerated.

Another object of the present invention is to provide an improved methodof reforming hydrocarbons of low octane number'to h drocarbons ofhighcctane number.

Another object is to provide a catalyst which will have the ability to"reio'rm both high sulfur and low-sulfur content hydrocarbon fractions.

A still further object r this" inyentionds to provide an improvedreforming catalyst contain otherwise to 2 ing amajor proportion of acracking component anda minor proportionof both an alkali metal and ametal from the group consisting of platium and palladium.

Numerous other objects will hereinafter appear from the disclosures ofthe specification and the appended claims, all taken in conjunction withthe accompanying drawing, which portrays diagrammatically thesuperiority of the n tan invention The catalysts of this invention arecomposite materials comprising, in general, major proportions of acracking component hereinafter indicated, a minor proportion of achemically combined alkali metal, and a minor proportion of platinum orpalladium. More particularly, the compcsited material comprises thecracking component, 0,5 to 5L0 weight percent of a chemically combinedalkali metal, and .01 to 2.5 Weight percent of platinum or palladium.All weight percentages mentioned in this specification are based on theweight of the final composite.

Ihe term cracking components," as hereinafter used, shall mean amaterial comprising silica' and ,at least one metal oxide from the groupconsisting of alumina, magnesia, thoria, and zircqn a, the composite ofsilica with the named o ides haying substantial activity for crackinghydrocarbons.

The cracking component may be derived from either naturally-occurring orsynthetically produced materials. Naturally-occurring materials includevarious aluminum silicates, particularly when acid treated to increasetheir activity for crackinghydrocarbons, such as Super Filtrol, etc.synthetically produced cracking components include silica-alumina,silica-zirconia, silica'ealumina-zirconia, silica-magnesia,silicaalumina-magnesia, silica-alumina-thoria, etc. These syntheticlilal e rials may be made in any suitable manner well known to the art,including separate, successive, or .coprecipitation methods ofmanufacture. The preferred synthetic cracking .c omponent,silica-alumina, may be manufactured by commingling an acid, such ashydrochloric acid, sulfuric acid, etc., with commercial water glassunder conditions to precipitate silica, washing with acidulated water orI a 7 remove sodium ions, commingling with an aluminum salt such asaluminum chloride, aluminum sulfate, aluminum nitrate, and either addinga basic precipitant, such as ammonium hydroxide to precipitate alumina,or rming 1 6 desflfi'i oxide or oxides by thermal decompositionof thesalt as the case may permit.

The preferred cracking component, silica-alumina, may contain from 20%to 95% by weight of silica with the remainder alumina, although amountsabove and below this range may also be used. A commercially availablesynthetic silicaalumina cracking catalyst is sold under the name Diakeland comprises about 87% silica and 13% alumina, prepared in generalaccording to the method outlined above. The cracking component may be inthe form of beads or granules either of regular or irregular size andshape. The granules may be ground or formed into pellets of uniform sizeand shape by pilling, extrusion, or other suitable methods. l V

The term chemically combin d alkali metal, as used herein and in theappended claims, refers to an alkali metal which is in true chemicalcombination with some other element of the catalyst and hence, does notinclude alkali metals in the metallic or free state, since it is clearthat under the elevated temperatures employed in reforming hydrocarbons,uncombined alkali metals would vaporize or combine with hydrocarbonswithin the reaction chamber.

The alkali metal may be either sodium, potassium, lithium, cesium, orrubidium and may be composited and combined with the cracking componentmentioned above in any suitable manner. Several illustrations are givenbelow, but it must be understood that the recitation of these methodsdoes not limit the invention to catalysts prepared according to thesemethods. The preferred method is to incorporate the alkali metal on thecracking component by a simple base exchange procedure which comprisesthe steps of soaking the cracking component pellets in asolution of asoluble alkali metal salt, draining off the excess alkali metal salt,washing the treated material with water, and drying. The alkali metalsalt solution may be in the form of inorganic salts such as thecarbonate, nitrate, sulfate, chloride, hydroxide, phosphate,dicarbonate, borate, aluminate, and the like, or salts of organic acidssuch as the acetate, propionate, and the like. The concentration of thealkali metal salt solution used in each particular instance will dependupon the solubility of the particular compound at the temperature oftreating and upon the desired concentration of the alkali metal in thecomposite catalysts.

Although the preferred method of incorporating the alkali metal is bybase exchange means as outlined above, the desired alkali metal contentmay also be incorporated by other procedures. One such method involvesthe incorporation of the desired amount of alkali metal during thepreparation of the cracking component. For instance, as described above,synthetic silicaalumina cracking catalysts are often prepared bydispersing a silica gel in a solution of an aluminum salt after which abasic precipitant, such as ammonium hydroxide is added to precipitatealumina on the silica gel. If an alkali metal hydroxide is employed asthe basic precipitant instead of ammonium hydroxide, the resultingcompound comprises an alkali metal aluminum silicate. This compound canthen be washed with a calculated quantity of a mineral acid to removeonly a part of the alkali metal so that the desired critical amount ofalkali metal will remain combined with the silica-alumina.Alternatively, the aluminum salt may be partially precipitated with analkali metal hydroxide (to incorporate the necessary amount of alkalimetal) following which the precipitation of the aluminum salt iscompleted with ammonium hydroxide and the composite calcined to removeammonia.

It is also possible to obtain the desired amount of alkali metal bytotal absorption on the cracking components of a measured quantity of analkali metal salt having a volatilizable or decomposable anion followedby drying and calcining.

The platinum or palladium may be composited with the cracking componentand chemically combined alkali metal by any suitable method known to theart. The preferred method is to admix an aqueous solution ofchloroplatinic acid or chloropalladic acid of suitable concentrationwith the cracking component containing the alkali metal. The mixture isthen dried and treated with hydrogen at elevated temperatures to reducethe chloride to the metal and to activate the catalyst. Although it hasbeen found preferable to add the alkali metal salt solution to thecarrier prior to impregnation with platinum or palladium, such additionmight instead be made after the impregnation with platinum or palladium.

The preparation of the composite catalyst by a simple base exchangeprocedure will be illustrated in the following examples. It should beunderstood, however, that the examples are given for the purpose ofillustration and the invention in its broader aspects is not limitedthereto.

EXAIVIPLE I 250 grams of fresh silica-alumina cracking catalyst (87%silica-13% alumina) pellets was soaked in an excess of demineralizedwater for 30 minutes, and thereafter centrifuged to give: 410 grams of awet catalyst. To this wet catalyst. was added 220 cc. of 1.44 N sodiumcarbonate: solution and the mixture was allowed to soakv for 30 minutes.The solid material was then drained to remove the excess salt solutionand. washed continuously with 2000 cc. of demineral-- ized water. Whentests of the wash water indi-- cated that no sodium ions were present,thetreated cracking component was dried at 212 F- for 16 to 18 hours.

200 grams of this dried material was treated. with 146 cc. of a .0174molar chloroplatinic acid solution. After this solution became absorbed.on the surface of the treated cracking component, the material was driedin an oven for 16 hours: at 212 F. for 2 hours at 450 F. in thepresence: of nitrogen, and then reduced at 450 F. for 6' hours in anatmosphere of hydrogen. Upon. analysis, this catalyst was found tocontain 1.3- weight percent of sodium and .27 weight percent; ofplatinum.

EXALEPLE H water showed that potassium ions were no longerpresent, thetreated silica-alumina was dried at 212 F. for 16 to 18 hours.

180 grams of this dried material was treated. with 132 cc. of .0172molar chloroplatinic acid solution. After the solution had been absorbedEXAMPLE III 350 cc. of a 2 N NazCOa solution (93 grams NfiZCO3-H20') in750 cc. of H was poured over 250 grams of fresh silica-aluminacrackingcatalyst and the mixture allowed to stand for hour. Thesupernatant liquid was poured-off and another 350 cc. portion of 2 NNazCOc solution added. After standing for minutes, the excess liquid wasdrained off and the solids washed 10 times with 350 cc. batches ofwater; The solids" were dried overnight in" an oven at 230 F. and'calcined at 900 F. for 1 hour. The resulting composite, after treatmentwith chloroplatinic acid as outlined in Examples I and II, wasfound' tocontain .16 weight" percent Weight percent of sodium.

The above examples illustrate howthe'instant catalyst may" be" preparedbybinglor multiple batch type procedures. However, the" catalyst can beequally well prepared by 'acontinuous percolation of the alkali metalsalt solution over platinum and 2.3

the silica-alumina until the desired amount of alkali metal has beenincorporated therewith.

Composite catalysts containing cesium, lithium, and rubidium may beprepared in a similar manner.

The'present invention entails the use of the catalyst described above ina reforming process. The generalprocedure in reforming-involves mixingthe hydrocarbon fraction to be treated with hydrogen and passing theadmixture in contact with the reforming catalyst. In carrying outreforming in accordance with this invention, temperatures in the rangeof 600 F. to.1000'F; .and'

preferably 700 F. to. 1000 F. may be used, depending upon the particularhydrocarbon feed employed andthe particular catalyst composition ratiobeing used: Ithas been foundipreferable,

tov preheat both the charge and the catalyst to these temperatures toachieve best results-,-.al-fthough either the charge or the catalystalone: could be so heated. The process is conducted at: pressures from100.to 1000p. s. i. and preferably.

from 500 to 800 p. s. i. Hourly liquidspace veloc-- ities (meaning theliquid volume of hydrocarbon per hour per volume of catalyst) may be inthe;

range of 0.1'to 10, preferablyin the range of 0.5 to 4.0. The reactionmay be carried out in'the presence of hydrogen in amounts from 1 to 20mols of hydrogen per mol of hydrocarbon. Un-

der these circumstances, using the instant-novel'- catalyst, it ispossible to obtain from petroleum distillate fractions, particularlygasoline frac-- tions, excellent yields of high octanev gasoline.

The hydrocarbons to be treated in the invention comprisepetroleum-distillate fractions, including naphthas, gasoline, and.kerosene, and

particularly gasoline fractions The gasoline fraction may be a. fullboiling range gasoline having an initial boiling point within the-rangeof' about 50 F. to about 90 F. and a final boiling.

point within the range of about 375 F. toabout 425 F., or it may be aselected fraction thereof whichusually will be a higher boilingfraction,

commonly referred to as naphtha r and generally. having an initialboiling point of from 150-? to about 250 F. and a final boiling pointwithin the the catalyst is suspended by the gaseous hydrocarbon streamor the moving bed' type process in which the catalyst and hydrocarbonare passed either concurrently or countercurrently to each other. Afterreforming, the products may be fractionated toseparate excess hydrogenand to recover the desired-fractions of'reformed'product.

In one manner ofio'peration of the process,- sufficient hydrogen willbeproduced in the reformingreaction to maintaina hydrogen partialpressuresufficient to saturate the hydrocarbon frag-'- ments formed therein.However, hydrogen from an extraneous source is added at the beginning ofthe operation and' usually itis desirable to recycle hydrogen withintheprocess after the starting operation in order to assure'asuflicienthydrogen atmosphere in the reaction zone; I-Iy'drogen serves to maintainthecatalyst activity by reducing or: preventing carbon deposition. Also,if desired, the hydrocarbon may be treated to remove sulfur prior toreformingathough such removal-is not necessary, and in fact, the us ofthe instant reforming catalyst produces equally good results with'or'without sulfur removal.

After a periodof service, it may be desirable to reactivatethecatalyst,and this may be readily accomplished by passing air or otheroxygencontaining gasestherethroughin order to burn carbonaceous depositsfrom the catalyst. 'A particularly suitable method of. regenerationcomprises effecting the regeneration at a temperature of about 900 F."to 050 F., starting with a gas containing about 2%. oxygen or less andgradu ally-increasing the oxygen concentration so that at the-end oftheregeneration period, pureair. is beingjpassed over thecatalyst..However, it is important that the temperature of regenera-' tion shouldnotexceed' 1000 F.,' as it has been found thattemperatures'in excess of1000 F. tend to impair the reforming activity'of the cat-'- alyst.

Table l below comprises'a series of reforming runs whereby a vaporizedEast Texas charge stock having the following specifications:

Reid vapor pressure 1.0 Percent sulfur .008 Octane number, clear(Research Method,

A. S. T. M. D-908-49T) 54.0 A. S. T. M. Distillation:

Qverpoint F 185 50% F 262 l F 334' Endpoint F 367 A. P; I. Gravity at 60F 55.5

was-mixed with hydrogen (10 mo1s of hydrogen per'mol of hydrocarbon) ata pressure of 500' p. s. i.', a liquid space velocity of 1.0 (ccjofliquid percc." of catalyst per hour) and contacted with I asilica-alumina-platinum-alkali metal catalyst havingthe'we'igh't percentof alkali' metal and platinum'indicated; at the tempertu'res' shown.These catalysts "vvi'are'prepared according" to the 7 methods set forthin Examples I and II. The volume percent recovery and clear researchmethod octane results were tabulated on the basis of a 4 pound Reidvapor pressure and plotted as carbonfeed nor is it limited to theyield-octane results obtained. The relationship of yield-octane resultsshown in Figure 1 for the two catalysts as been found to hold true forall feed curve A in Figure 1. V 5 stocks tested. Other charge stocksused with 7 Table 1 I Alkali Metal Sodium Sodium 'Sodlum PotassiumPotassium Cesium AlkaliMetal (Wt. 2.9 2.3 1.3 -'2.4- 1.4 3.6

Platinum (Wt. Percent) .12 .25 .27 22. .18 .24

Temperature(F.) 850 920 850 920 850 920 .850 .920 s50 e 920 Yield (Vol.Percent of charge) 99.8 93.2 97.3 90.4 85.5 72.8 97.5 89.5 81.3 70.078.4

Research Octane (Clear) 69.9 80.0 68.0 76.4 83.8 04.2 66.9 80.7 85.695.2 90.0

As hereinbefore set forth, a multitude of reforming catalysts have beensuggested in the prior art. Among these, the combination of platinum orpalladium with a cracking component com prising silica and one or moremetal oxides from the group consisting of alumina, magnesia, thoria, andzirconia havebeen mentioned, and particularly the combination of silica,alumina, and platinum. In order to clearly show the marked superiorityof the instant catalysts over a silica-alumina-platinum catalyst notcontaining an alkali metal, many comparative tests were conducted.

The only method of comparing the reforming ability of two reformingcatalysts is by comparing the yield-octane relationship obtainable fromeach. In order to make these relationships truly comparable, it isnecessary to reform aliquot portions of the identical charge stock witheach catalyst. If the same charge stock is not used in each case, novalid comparison of yield-octane results can be made since eachdifferent charge stock is composed of different components andconsequently, each different charge stock varies in its ability to bereformed. Also, in order to make a valid comparison of the yield-octaneresults, it is necessary that the productsv be condensed at the sametemperature and compared at the same Reid vapor pressure.

Therefore, to produce a silica-alumina-platie num catalyst for purposesof comparison, the

steps of Examples I and II were carried out with the exception that thealkali metal treating step was omitted. This catalyst was then used toreform the identical East Texas hydrocarbon charge stock employed in theruns of Table 1 and under the same operating conditions. The results aretabulated in Table 2 below and plotted in curve B of Figure 1.

A comparison of Tables 1 and 2 and the corresponding curves A and 13" ofFigure 1 shows the striking superiority of the silica-aluminaplatinum-alkali metal catalyst over a silica-aluminaplatinum catalystcontaining no alkali metali Figure 1, attached hereto, is presentedprimariy to show the comparative values of the abovementioned catalystand. is not intended to limit applicants invention to this particularhydrothe instant catalysts may give higher yields and higher octanevalues, yet the relative improvement evidenced by the instant catalystwill'generally the same.

It has heretofore been mentioned that the amounts of alkali metal whichcan be composited with the cracking component and platinum lies betweenoptimum limits. If amounts less than 0.5% are used, the final catalystwill show yieldoctane relationships falling in the neighborhood of thecurve B" in Figure 1, i. e., these catalysts are similar tosilica-alumina-platinum having no alkali metal composited therewith andtherefore are inferior. The upper limit of 4.0% was selected for thereason that catalysts having amounts of alkali metal in excess of thisamount were too inactive, that is, they gave negligible octaneimprovement. However, in the case of cesium and rubidium, which havehigher atomic weights, amounts somewhat in excess of 4.0% may be usedwithout obtaining an inactive catalyst.

It has also been mentioned that the amounts of platinum or palladiumshould range between 0.01% by weight to 2.5% by weight of the finalcomposite. Amounts less than 0.01% result in too low reforming activity,i. e., negligible octane improvements, amounts greater than 2.5% arelikewise undesirable for the reason that such catalysts result inexcessive cracking.

A further highly advantageous property of thesilica-alumina-platinum-alkali metal catalyst resides in its ability toreform hydrocarbon charge stocks containing large amounts of sulfurcompounds. As is well-known in the art, charge stocks containing evensmall amounts of sulfur compounds are much more difficult to reform thansulfur-free charge stocks. In addition, the vast majority of reformingcatalysts known heretofore are deleteriously affected by asulfur-containing feed with the result that the activity and life ofthese catalysts are impaired As a consequence, in early beenspecifically pointed out that the hydrocarbon charge should bedesulfurized so as to make it practically sulfur-free. Variousdesulfurization processes are known, but their use entails additionalequipment and considerable expense. The instant catalysts, however, arenot deleteriously affected by sulfur-containing charge stocks, but tothe contrary are capable of reforming sulfur-containing charge stockswith the same degree of success as sulfur-free charge stocks. This.highly advantageous property results in increased economy of operationby eliminating the'necessity for an expensive pre-desulfurization step.

The results tabulated in Table 3 below illustrate that the presentcatalysts are highly emcient for reforming a hydrocarbon charge stockcontaining sulfur compounds. The data shown in Table 3 was obtained bypassing a West Texas Permian charge stock having the followingproperties:

Reid vapor pressure (lbs) .5 Percent sulfur .32 Octane number, clear(Research Method,

A. S. T. M. D-908-49T) 48.9 A. S. T. M. distillation:

Overpoint F 193 50% F 275 90% F 334 Endpoint F 384 A. P. I. gravity (at60 F.) 53.2

in admixture with hydrogen mols of hydrogen per mol of hydrocarbon) at apressure of 500 p. s. i., a liquid space velocity of 1.0 (cc. of liquidper cc. of catalyst per hour) over a silicaalumina-platinum-alkali metalcatalyst having the weight percent of alkali metal and platinumindicated, and at the temperatures shown in Table 3 below. Thesecatalysts were prepared according to the methods set forth in ExamplesI, II, and III. The volume percent recovery and research method octaneresults were tabulated on the basis of a 4 pound Reid vapor pressureproduct.

Table 3 Alkali Metal Sodium Sodium Sodium Alkali Metal (Wt. percent) 2.32.9 1.35 Platinum (Wt., percent) .16 .25 .25

Temperature (F.) 850 920 850 920 850 920 Yield (Vol. percent of Charge)99.4 91. 99.7 94.7 92.0 79.2 Research Octane (Clear)... 68.5 79.1 68.178.0 76.7 90.2

to increase the anti-knock value thereof which comprises admixinghydrogen with said fraction and passing said admixture at reformingconditions including a temperature within the range of 600 F. to 1000 F.and a pressure of from to 1000 p. s. i. over a catalyst consistingessentially of a cracking component, 0.01 to 2.5 weight percent of ametal from the group consisting of platinum and palladium, and 0.5 to4.0 Weight percent of a chemically combined alkali metal, said crackingcomponent comprising silica and at least one metal oxide from the groupconsisting of alumina, magnesia, thoria, and zirconia.

2. The process according to claim 1 wherein the catalyst consistsessentially of 0.01 to 2.5 weight percent of platinum, 0.5 to 4.0 weightpercent of chemically combined alkali metal and a cracking componentcomprising silica and alumina.

3. The process according to claim 1 wherein the catalyst consistsessentially of 0.01 to 2.5 weight percent of platinum, 0.5 to 4.0 weightpercent of chemically combined sodium, and a cracking componentcomprising silica and alumina.

4. A catalyst consisting essentially of a cracking component, 0.01 to2.5 weight percent of a metal from the group consisting of platinum andpalladium, and 0.5 to 4.0 weight percent of a chemically combined alkalimetal, said cracking component comprising silica and at least one metaloxide from the group consisting of alumina, magnesia, thoria, andzirconia.

5. A catalyst consisting essentially of 0.01 to 2.5 weight percent ofplatinum and 0.5 to 4.0 weight percent of a chemically combined alkalimetal, and a cracking component comprising silica and at least one metaloxide from the group consisting of alumina, magnesia, thoria, andzirconia.

6. A catalyst consisting essentially of 0.01 to 2.5 weight percent ofplatinum, 0.5 to 4.0 weight percent of chemically combined sodium, and acracking component comprising silica and alumina.

FRANK G. CIAPETTA.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,249,337 ViSser et al July 15, 1941 2,317,683 GreensfelderApr. 27, 1943 2,474,440 Smith et al June 28, 1949 2,478,916 Haensel Aug.16, 1949 2,550,531 Ciapetta Apr. 24, 1951

1. A PROCESS FOR REFORMING A GASOLINE FRACTION TO INCREASE THEANTI-KNOCK VALUE THEREOF WHICH COMPRISES ADMIXING HYDROGEN WITH SAIDFRACTION AND PASSING SAID ADMIXTURE AT REFORMING CONDITIONS INCLUDING ATEMPERATURE WITHIN THE RANGE OF 600* F. TO 1000* F. AND A PRESSURE OFFROM 100 TO 1000 P.S.I. OVER A CATALYST CONSISTING ESSENTIALLY OF ACRACKING COMPONENT, 0.01 TO 2.5 WEIGHT PERCENT OF A METAL FROM THE GROUPCONSISTING OF PLATINUM AND PALLADIUM, AND 0.5 TO 4.0 WEIGHT PERCENT OF ACHEMICALLY COMBINED ALKALI METAL, SAID CRACKING COMPONENT COMPRISINGSILICA AND